Various therapies, known to or stemming from traditional Oriental medicine, rely on pressure, needle, electric and/or magnetic stimulation of specific points in the human body. Many of these therapies emphasize energy balancing; consider Chinese acupuncture (Zhen Jiu) which aims to balance a vital energy known as Qi. According to traditional acupuncture, Qi interacts with vital substances such as Xue (blood), Jing (essence), Shen (spirit), and Jin Ye (bodily fluids). For example, Xue follows Qi through the body primarily via twelve main energy ducts called meridians wherein each of these meridians connects to one of twelve organs. Acupuncture models typically show meridians as lines running and occasionally crossing throughout the body wherein individual acupuncture points, or acupoints, fall along the meridians. According to the practice of acupuncture, acupoint stimulation can release blockages, balance Qi and restore the body to its natural state. A practitioner of acupuncture typically stimulates an acupoint through manual manipulation of a fine needle inserted subcutaneously at an acupoint; whereas, a practitioner of acupressure (Zhi Ya) may apply pressure to stimulate an acupoint. More recently, however, electric and/or magnetic energy have been used to stimulate acupoints, for example, consider electroacupuncture, which has generally proven to be more convenient and effective than manual stimulation.
While Western medicine has typically viewed acupuncture relatively simply (e.g., as synonymous with nerve stimulation), recent studies support the Oriental view that meridians and acupoints have special significance. In particular, various studies suggest that acupoint stimulation produces a result essentially different than that of non-acupoint stimulation. To elucidate such differences, researchers have begun using functional magnetic resonance imaging (fMRI) or positron emission tomography (PET) to map brain activity responsive to stimulation at acupoints and non-acupoints. A study by Cho et al., “New findings of the correlation between acupoints and corresponding brain cortices using functional MRI,” Proc. Natl. Acad. Sci. USA, 95(5):2670-2673 (1998), showed that ancient acupuncture literature correctly associated acupoints with particular organs or brain activity. More specifically, Cho et al. demonstrated that stimulation at acupoint BL.67 (Zhi Yin), located on the foot and known for treatment of eye disorders, activated the occipital lobes whereas stimulation of non-acupoints (e.g., points displaced by two cm to five cm) did not activate the occipital lobes. A later study by Siedentopf et al., “Functional magnetic resonance imaging detects activation of the visual association cortex during laser acupuncture of the foot in humans,” Neurosci. Lett., 327(1):53-56 (2002), confirmed that acupoint stimulation at BL.67 activated the visual cortex. These studies lend credence to a wealth of traditional therapies based on acupoint stimulation.
Another study, by Wu et al., “Central nervous system pathway for acupuncture stimulation: localization of processing with functional MR imaging of the brain—preliminary experience,” Radiology, 212:133-141 (1999), examined acupuncture at two acupoints, well-known for analgesia, and “minimal” acupuncture at non-acupoints (e.g., points displaced by 2 cm to 3 cm). Wu et al. reported that acupuncture at LI.4 (Hegu) and ST.36 (Zusanli) produced bradycardia and activation of the hypothalamus and nucleus accumbens and deactivation of the rostral part of the anterior cingulated cortex, amygdala formation, and hippocampal complex; whereas, minimal acupuncture at the non-acupoints produced activation of the supplementary motor cortex, parietal operculum, and frontal operculum. Wu et al. also detected a more extensive activation of the hypothalamus for stimulation of the LI.4 acupoint compared to the ST.36 acupoint and noted that this result coincides with clinical observations that show stimulation at LI.4 produces a stronger analgesic effect than stimulation at ST.36. On the basis of their results, Wu et al. hypothesized that bradycardia is characteristic of an acupuncture-related autonomic response and that acupuncture analgesia is associated with deactivation of limbic areas and attenuation of the affective response to pain. Wu et al. also recognized that acupuncture often has analgesic and non-analgesic effects. A later study by Hsieh et al., “Activation of the hypothalamus characterizes the acupuncture stimulation at the analgesic point in human: a positron emission tomography study,” Neurosci. Lett., 307(2):105-108 (2001), also examined stimulation at the LI.4 acupoint and a non-acupoint. Hsieh et al. found that stimulation of the LI.4 acupoint activated the hypothalamus while stimulation of the non-acupoint did not. These studies support the traditional practice of acupoint stimulation for treatment of pain as well as other disorders.
Overall, studies using modern imaging modalities have effectively demonstrated that acupoint stimulation can produce therapeutic action. In the realm of cardiac pacing and/or stimulation therapies, acupoint stimulation holds promise. However, Fujiwara et al., as reported in “The influence of low frequency acupuncture on a demand pacemaker,” Chest, 78:96-97 (1980), found that low frequency acupuncture caused electromagnetic interference capable of interfering with demand sensing. Indeed, electroacupuncture is often contraindicated for patients having implanted pacing and/or stimulation devices, especially devices that rely on sensing. Therefore, a need exists for methods, devices and/or systems that allow cardiac pacing and/or stimulation therapy patients to benefit from electric and/or magnetic acupoint stimulation therapy.
U.S. Pat. No. 7,321,792 to Min et al., entitled “Pacing Therapy and Acupuncture,” addressed some of these needs. In various examples described therein, an implantable cardiac therapy device detects the need for anti-arrhythmia therapy and communicates with an implanted slave device, which, in turn, delivers power to an acupuncture point that may have an analgesic, anti-arrhythmic or other beneficial effect. Alternatively, the slave device notifies the patient (or caregiver) to administer a potentially beneficial acupuncture therapy. In one example, an implantable cardioverter defibrillator (ICD) detects an arrhythmia that warrants a defibrillation shock (such as an episode of atrial fibrillation (AF) that warrants a cardioversion shock) and then communicates pertinent information to an external device to warn the patient of caregiver. Stimulation is delivered via an external device at an acupuncture site in the arm in an effort to minimize pain associated with the imminent shock.
Hence, the Min et al. patent sets forth various techniques for providing stimulation at acupuncture points. Some aspects of the present invention are directed to expanding or modifying these stimulation techniques to achieve additional or alternative benefits, particularly for use with a CRMD.
Another stimulation technique that may be used in conjunction with a CRMD is spinal cord simulation (SCS.) Several studies have connected SCS with cardiac electrophysiology. For example, studies by Olgin et al. and Jacques at al. indicated that SCS blunts the effects of sympathetic stimulation and enhances the effects of vagal stimulation. (See, Olgin et al., JCE 2002 and Jacques et al. JCE 2011.) Cardinal et al. indicated that SCS suppressed neurally-mediated atrial brady- and tachyarrhythmias. (See, Cardinal et al., AJP Reg Integ Comp Physiol 2006.) Issa et al. and Lopshire et al. showed results indicating SCS prevented ischemia related ventricular tachyarrhythmias. (See, Issa at al., Circ 2005 and Lopshire et al., Circ 2009.) Insofar as heart failure is concerned, Lopshire at al. (Circ 2009) studied SCS in systolic heart failure with myocardial infarction and rapid RV pacing. Their results showed therapeutic benefits of SCS on clinical parameters of decreased heart rate, increase in systolic blood pressure, decrease in weight gain, and increase in oxygen saturation. The results also showed a decrease in spontaneous and ischemic-challenged ventricular tachycardia (VT), brain natriuretic peptide and norepinephrine, and reverse remodeling with increase in left ventricular (LV) ejection fraction and decrease in LV dimension. Effect of SCS alone was shown to be greater than SCS with medications.
At least some implantable systems have been proposed that employ both a CRMD and a SCS device. See, for example, U.S. Pat. Nos. 6,349,233 and 5,792,187, both to Adams. SCS for use in conjunction with an implanted pacemaker or heart monitor to treat angina (activated in response to detection of ischemia) is discussed in U.S. Pat. No. 5,199,428 issued to Obel et al. See, also, U.S. Pat. No. 6,134,470 to Hartlaub.
Accordingly, both SCS and acupuncture represent promising techniques that may be exploited in connection with cardiac rhythm management and heart failure management. Preferably, the CRMD would control the operation of the SCS or acupuncture device to coordinate cardiac rhythm management and heart failure management. However, it may be impractical (at least in some cases) to implant both a SCS device and a CRMD within a given patient, especially if the CRMD is intended to control the operation of the SCS. In this regard, the CRMD is typically implanted within an anterior pectoral region of the chest near the heart whereas a SCS device is usually implanted in the buttocks or abdomen with its leads along the spinal cord. Likewise, it may be impractical to implant both a CRMD and a separate acupuncture stimulation controller within a patient, at least for stimulating acupuncture points remote from the implant location of the CRMD.
Accordingly, aspects of the invention are directed to providing a more practical implantable system that uses a CRMD to control neurostimulation without the need for a separate SCS controller or a separate acupoint neurostimulation controller. Other aspects of the invention are directed to greatly expanding the capability of a CRMD to coordinate neurostimulation at acupuncture sites to achieve a range of benefits such as: modulating cardiac functions to prevent or mitigate heart failure progression; preventing or mitigating arrhythmia; improving the success rate of antitachycardia pacing (ATP); controlling hypertension; controlling respiration to treat Cheyne-Stokes respiration (CSR) and sleep apnea; and reducing pain from angina or from AF shocks or VT/ventricular fibrillation (VF) shocks.